Go to search hashtag and enter any hastag in this case we use #Party
If you are connected with a mobile device to bigscreencast software:
Find at the top left of your screen within the list of photos, an icon saying “Connect Chromecast”.
Click on it, select the destination device and a welcome screen will be displayed in your bigscreen,
Result on the big screen updated from your mobile phone will look like this
now every time you click “Cast” button the new photo and comment will cast to the chromecast device selected, updating the screen content from your mobile device.